1. Field of the Invention
The present invention relates to lighter-than-air balloons, and more particularly, to lighter-than-air balloons having a rigid skeleton.
2. Description of the Related Art
Generally, it has been difficult to fabricate balloons with continuously curved shapes, and well-defined corners, or edges. Most balloons are formed in spherical shapes in order to allow the greatest volume for the least surface area. Also, the thin material of the balloon naturally becomes spherical as pressure is increased. To achieve the desired non-spherical shape, then, it is necessary to provide a supporting frame to maintain the thin material of the balloon. However, in the past, the weight of such frames, even when the most efficient materials for such purposes were selected, typically required a displaced volume of such size that fabrication for home use or the like would have been impractical. Consequently, helium balloons are typically formed in spherical shapes with some type of tethering device attached for maintaining control of the balloon's elevation.
U.S. Pat. No. 4,032,086, issued Jun. 28, 1977 to W. Cooke, discloses an aerostat or aquastat in which a sealed envelope of flexible material is mounted on a flexible frame which can be caused to expand the envelope after it has been evacuated of internal gas, thereby setting up a vacuum or partial vacuum condition in the envelope. By controlling the frame to adjust the volume of the envelope, the lift or buoyancy of the device can be controlled in flight or precisely determined before ascent.
U.S. Pat. No. 4,038,777, issued Aug. 2, 1977 to S. Schwartz, discloses a gas filled, balloon-like object capable of defining a non-spherical shape. A high modulus graphite impregnated epoxy material is used to prevent distortion of the inflated object. Strings or weights are required to prevent upward ascent of the balloon.
U.S. Pat. No. 4,113,206, issued Sep. 12, 1978 to D. Wheeler, discloses a lighter-than-air apparatus, including a thin, pliable air-tight cuter envelope disposed in overlying relationship over a light-weight, coarse-opening inner frame of a spherelike shape.
Other devices relating to balloons and lighter-than-air apparatuses include U.S. Pat. No. 2001/0003505 A1 issued Jun. 14, 2001 to T. Bertrand, which discloses a lighting apparatus secured to a balloon by string under tension; U.S. Pat. No. 4,925,426 issued May 15, 1990 to C. Lovik, which discloses an open skeletal frame of rigid rod-like formers made of thin strands of plastic, wire, or the like and which permits the insertion of an uninflated balloon of conventional shape and size into the interior thereof so that upon inflation of the balloon, the latex sidewall material of the balloon projects outwardly through the openings of the formers to produce bulbous projections; U.S. Pat. No. 5,115,997, issued May 26, 1992 to J. Peterson, which discloses a tethered surveillance balloon having a relatively low lift-to-weight ratio; U.S. Pat. No. 5,115,998, issued May 26, 1992 to L. Olive, which discloses a double-walled, annular balloon which requires less gas to inflate than its volume would indicate; U.S. Pat. No. 5,334,072, issued Aug. 2, 1994 to M. Epstein, which discloses an inflatable body, such as a balloon, and holder assembly therefore; U.S. Pat. No. 5,882,240, issued Mar. 16, 1999 to B. Larsen, which discloses a toy blimp; U.S. Pat. No. 6,276,984, issued Aug. 21, 2001 to K. Komaba, which discloses a balloon having adhering members disposed upon its surface; Japanese Patent No. 1238890, published Sep. 25, 1989, which discloses plastic film balloons in animal and other complex shapes.
Similar reference characters denote corresponding features consistently throughout the attached drawings.